The appearance of rubber articles can deteriorate in the presence of ozone (O3), an allotropic form of oxygen that exists in the atmosphere. Surface cracks and other cosmetic defects sometimes form.
Petroleum wax, secondary aromatic amines, quinoline, and furan derivatives are some examples of substances that have been incorporated into rubber formulations to reverse or prevent cosmetic deterioration due to ozone. Substances that prevent the effects of ozone are sometimes referred to as antiozonants. However, some antiozonants can migrate to the surface of the rubber article, causing discoloration.